The First Law of Thermodynamics Practice Test

A rigid, sealed tank of gas is the system. Take $Q>0$ into the gas and $W>0$ done by the gas. The tank is heated so that $Q=+1200,\text{J}$ is transferred to the gas; because the tank is rigid, the boundary does not move. Which statement correctly describes the gas’s internal energy change?

A gas in a piston-cylinder is the system. Take $Q>0$ into the gas and $W>0$ done by the gas. During a process the gas does $W=+300,\text{J}$ of work, and its internal energy does not change ($\Delta U=0$). Which statement correctly describes the heat transfer?